1/25 TRD workshop, Sibiu, Aug 20 − 23, 2008 Kai Schweda

Collective Flow of QCD – matter atHighest Collider Energies

Kai Schweda, University of Heidelberg / GSI Darmstadt

2/25 TRD workshop, Sibiu, Aug 20 − 23, 2008 Kai Schweda

Quark Gluon Plasma

Source: Michael Turner, National Geographic (1996)

Quark Gluon Plasma:

(a) Deconfined and

(b) thermalized state of quarks and gluons

Study partonic EOS at LHC(?) Probe thermalization using heavy-quarks

3/25 TRD workshop, Sibiu, Aug 20 − 23, 2008 Kai Schweda

Outline

Identify and study QCD bulk-matter with

partonic degrees of freedom:

• Transverse Radial and Elliptic Flow:

- some results from RHIC

- some estimates for LHC

• Heavy – quark collectivity

• Summary

4/25 TRD workshop, Sibiu, Aug 20 − 23, 2008 Kai Schweda

Mid − rapidity DensitiesPHOBOS fit

HIJING BBar

Armesto et al.

AMPT

Eskola

CGC

KLN

ASW

DPMJET-III

EHNRR

at LHC, dN/dη ≈ 1000 − 2000 (detectors designed for 8000)

estimate energy densityTheory points: HI at LHC – last call for predictions, CERN, May 2007.PHOBOS compilation: W. Busza, SQM07.

dy

dE

R

TBj

0

2

11

!"# =

5/25 TRD workshop, Sibiu, Aug 20 − 23, 2008 Kai Schweda

EoS from Lattice QCD

1) Large increase in ε !

Large increase in Ndof:

Hadrons vs. partons

2) TC ~ 160 MeV

3) Boxes indicate max. initial

temperatures

Longest expansion

duration at LHC

Expect large partonic

collectivity at LHCZ. Fodor et al, JHEP 0203:014(02)

C.R. Allton et al, hep-lat/0204010

F. Karsch, Nucl. Phys. A698, 199c(02).

LHC ?RHICSPS

TRD workshop, Sibiu, Aug 20 − 23, 2008 Kai Schweda

Hadron Yield − Ratios

1) At RHIC: Tch = 160 ± 10 MeV µB = 25 ± 5 MeV

2) γS = 1.

➠ The hadronicsystem isthermalized at RHIC.

3) Short-lived resonancesshow deviations.

➠ There is life afterchemical freeze-out.

RHIC white papers - 2005, Nucl. Phys. A757, STAR: p102; PHENIX: p184;Statistical Model calculations: P. Braun-Munzinger et al. nucl-th/0304013.

7/25 TRD workshop, Sibiu, Aug 20 − 23, 2008 Kai Schweda

Pressure, Flow, Pressure, Flow, ……

pdVdUd +=!"

Thermodynamic identity

σ – entropy p – pressureU – energy V – volumeτ = kBT, thermal energy per dof

In A+A collisions, interactions among constituentsand density distribution lead to: pressure gradient ⇒ collective flow

⇔ number of degrees of freedom (dof)⇔ Equation of State (EOS)⇔ cumulative – partonic + hadronic

8/25 TRD workshop, Sibiu, Aug 20 − 23, 2008 Kai Schweda

Momentum Distributions*Momentum Distributions*2

][(

GeV

/

2c)

-1dy

dpN

dT

π

][GeV/ cpT

π

K (dE/dx)

p

Λ

K (kink)

*Au+Au @130 GeV, STAR

Tth=107±8 [MeV]<βt>=0.55±0.08 [c]n=0.65±0.09χ2/dof=106/90

solid lines: fit range

• Typical mass ordering in

inverse slope from light π to

heavier Λ

• Two-parameter fit describes

yields of

π, K, p, Λ

• Tth = 90 ± 10 MeV

• <βt> = 0.55 ± 0.08 c

Disentangle

collective motion from

thermal random walk

π

K (dE/dx)

p

Λ

K (kink)

9/25 TRD workshop, Sibiu, Aug 20 − 23, 2008 Kai Schweda

1) Multi-strange hadrons 1) Multi-strange hadrons φφand and ΩΩ freeze-out earlierfreeze-out earlierthanthan ((ππ, , KK, , pp))

Collectivity prior to Collectivity prior tohadronizationhadronization

2) Sudden single freeze-out*:2) Sudden single freeze-out*:Resonance decays lower Resonance decays lower TTfofofor (for (ππ, , KK, , pp)) Collectivity prior to Collectivity prior to

hadronizationhadronization

PartonicPartonicCollectivityCollectivity

Kinetic Freeze-out at RHIC

STAR Data: Nucl. Phys. A757, (2005 102),*A. Baran, W. Broniowski and W. Florkowski, Acta. Phys. Polon. B 35 (2004) 779.

STAR Preliminary

TRD workshop, Sibiu, Aug 20 − 23, 2008 Kai Schweda

Slope Parameter Systematics

At RHIC, φ, Ξ, Ω, and J/ψ show collective motion in200 GeV Au + Au central collisions!

!

f = A •exp "mT /Tslope( )

SPS results:No collective motion for multi-strange and charm hadrons!

RHIC results:Collective motion for multi-strange and charm hadrons!

〈βp〉 ≥ 0.2c

PHENIX (π, K, p, J/ψ): PRC69, 034909(04), QM05; STAR (φ, Ξ, Ω): QM05.

11/25 TRD workshop, Sibiu, Aug 20 − 23, 2008 Kai Schweda

Anisotropy Parameter v2

y

x

py

px

coordinate-space-anisotropy ⇔ momentum-space-anisotropy

!

" =#y 2 $ x 2%

#y 2 + x2%

v2

= cos2& , & = tan$1(py

px)

Initial/final conditions, EoS, degrees of freedom

12/25 TRD workshop, Sibiu, Aug 20 − 23, 2008 Kai Schweda

v2 in the Low-pT Region

P. H

uovinen, private comm

unications, 2004

- Minimum bias data! At low pT, model result fits mass hierarchy well!- Details do not work, need more flow in the model!

13/25 TRD workshop, Sibiu, Aug 20 − 23, 2008 Kai Schweda

v2 of Multi-strange Hadronsφ and Ω

Strange-quark flow − partonic collectivity at RHIC!NB: Φ → K+ + K- (BR 49%)

Φ → e+ + e- (BR 0.03%)

QM05 conference: M. Oldenburg; nucl-ex/0510026.

14/25 TRD workshop, Sibiu, Aug 20 − 23, 2008 Kai Schweda

Collectivity − Energy Dependence

Collectivity parameters <βT>

and <v2> increase with energy

Two extreme scenarios:

(a) Tfo ≈ Tch AND βT ≈ 0.8

pure partonic

collectivity at LHC!

(b) Tfo ≈ Tch , βT ≈ 0.3

no collectivity,

no QGP !

K.S., ISMD07, arXiv:0801.1436ﾊ[nucl-ex].

15/25 TRD workshop, Sibiu, Aug 20 − 23, 2008 Kai Schweda

Elliptic Flow at LHC

Theory points: C.M. Ko – last call for predictions, CERN, May 2007.

“Elliptic flow is larger forpions but smaller forprotons at LHC than atRHIC”.

This is expectedfrom simple, hydro-like blast-wave fits !

larger collectiveflow: mass orderingmore pronounced !

sensitive topartonic EOS !

TRD workshop, Sibiu, Aug 20 − 23, 2008 Kai Schweda

Quark Masses

1) Higgs mass: electro-weaksymmetry breaking (currentquark mass).

2) QCD mass: Chiral symmetrybreaking (constituent quarkmass).

➩ Strong interactions do notaffect heavy-quarkmasses.

➩ Important tool for studyingproperties of the hot/densemedium at RHIC and LHC.

➩ Test pQCD predictions atRHIC and LHC.

Total quark mass (MeV)

X. Zhu, M. Bleicher, K.S., H. Stoecker, N. Xu et al., PLB 647 (2007) 366.

17/25 TRD workshop, Sibiu, Aug 20 − 23, 2008 Kai Schweda

Predictions for LHC

large charm production at LHC

strong regeneration of J/ψ

striking centrality dependence

Signature for QGP

formation !

Initial conditions at LHC ?

Need to measure total

charm production in PbPb !

Also: check ψ’ /ψ ratio vs stat.model predictions

A. Andronic et al., Phys. Lett. B 652 (2007) 259.

∼σcc

18/25 TRD workshop, Sibiu, Aug 20 − 23, 2008 Kai Schweda

Beauty Correlations

b-bbar are correlated

• Pair creation: back to back

• Gluon splitting: forward

• Flavor excitation: flat

Correlations vanish

frequent interactions

among partons !

probe light-quark

thermalization !

Pythia calcs.: G. Tsiledakis.

19/25 TRD workshop, Sibiu, Aug 20 − 23, 2008 Kai Schweda

Where does all the charm go?

D0

D±

Ds

Λc

J/ψ

Measure open-charm mesons, e.g. D0 and D* to address:(a) total charm production(b) heavy-quark collectivity

Statistics plot: H. Yang and Y. Wang.

D*±

20/25 TRD workshop, Sibiu, Aug 20 − 23, 2008 Kai Schweda

How to measure Heavy-Quark Production

Measure- single e ⇒ total (c+b) production- D0 and D* ⇒ heavy quark collectivity and total c (+b) cross section- B → J/ψ + X, B+, Λb ⇒ disentangle c and b !

21/25 TRD workshop, Sibiu, Aug 20 − 23, 2008 Kai Schweda

Measure secondary vertex

Direct reconstruction of D0

precise measurement

of total heavy-quark yield

address heavy – quark

collectivity !

D0 − Meson Performance

ALICE: PPR.vol.II, J. Phys. G 32 (2006) 1295.

22/25 TRD workshop, Sibiu, Aug 20 − 23, 2008 Kai Schweda

D*− meson Identification

D*± analysis: Yifei Wang, Heidelberg

D*+ → D0 + π+

Identify D*+

throughΔM[D*+ - D0]

Subtract resonance

decay to D0

Two different

methods to address

total charm

production

23/25 TRD workshop, Sibiu, Aug 20 − 23, 2008 Kai Schweda

J/ψ − Identification

J/ψ analysis: Dirk Krumbhorn, HeidelbergAlso: Wolfgang Sommer, Frederik Kramer, Frankfurt

J/ψradiation tailγ →e+ + e-

J/ψ → e+ + e-

Identify throughinvariant mass

e → e + γ leads to

signal loss (30%)

e±-pairs form

photon conversion

at low inv. Mass

24/25 TRD workshop, Sibiu, Aug 20 − 23, 2008 Kai Schweda

At RHIC, global observablesscale with multiplicity

p+p @10TeV, dNch/dη up to 100

Similar to mid-central Cu+Cucollisions at top RHIC energy

Look for collectivity inp+p @ LHC !

Collectivity in p+p @ 10 TeV ?

PYTHIA 14 TeV

ALICE MC data: A. Dainese, HP2008;PHOBOS multiplicity: nucl-ex 0709.4008;Z. Chajecki and M. Lisa, arXiv:0807.3569 [nucl-th].

ALICE pixel trigger:

25/25 TRD workshop, Sibiu, Aug 20 − 23, 2008 Kai Schweda

Summary

Bulk properties at LHC:

Tch ≈ 160 ± 10 MeV, µB ≈ 0 – 5 MeV

Tfo ≈ Tch all collectivity from partonic stage

<βT> = 0.8 ± 0.05 (c), <v2> ≈ 0.08

In Pb+Pb (p+p) measure spectra, correlations and v2 of:

D0, D*±, D+, Ds, J/ψ, ψ’, Λb, ϒ

to identify and characterize QGP !

ALICE with ITS, TPC, TRD and ToF

is well suited for these studies